Parallel Processing
Parallelism plays a significant role in processing massive
databases. Teradata pioneered some of the key technology.
All major vendors of database management systems now
offer data partitioning and parallel query processing
technology. The article by Dewitt and Gray provides an
overview of this area28 . One interesting technique relevant to
the read-only environment of decision support systems is that
of piggybacking scans requested by multiple queries (used in
Redbrick). Piggybacking scan reduces the total work as well
as response time by overlapping scans of multiple concurrent
requests.